Construction and outdoors decoration at present largely depend upon wooden products, causing the dramatic increase of destruction of forests, and deterioration of environment. Therefore, it is of great importance to find and exploit new techniques and new products that protect the environment and economize resources. As some examples, resin materials have been used to replace a wooden material. While such resin materials may have desirable qualities such as anti-impact, anti-aging, anti-erosion, anti-water, anti-humidity and fire-resistance, they lack the outer appearance and original smell of true wood, and are unable to satisfy the aesthetic needs of people in the modern society.
Chinese Patent Application (95117967.5) involves a kind of composite (board/profile) and its fabrication methods, which mainly includes the breaking up and rubbing of wood material waste and scraps to obtain wooden flour with smaller particles, which are blended with a coupling agent, tackifier, stabilizer and thermal plasticity pastern, and then put into a high-speed blender to undergo even and enough blending with steam being evaporated to become the core material, which is to be fed into a combined extrusion line. The core material is made through co-extrusion by a principal extruder. Thermal plastic flour (particle) with plasticity and good compatibility is chosen according to specification requirements of the products, and is fed into a vice extruder in the production line of combined extrusion, to produce the outer layer that envelopes part of or the whole of the core material, for example to fabricate board or profile products. Though this method avoids the large consumption of timber that is needed by traditional technology of fabrication of profile and board, the plastic material adopted in the outer envelope, such as PVC, PP, PE, ABS and PC, still lacks the quality of wood on appearance and smell, therefore, has failed to satisfy the aesthetical needs of people in modern society. In addition, the plastic flour with plasticity and the wooden flour that are adopted in this method are present in the percentage of 80-20 and 20-80 respectively, which has further made it hard to achieve even blending between them, and hard to produce the boards or profiles with high standard.
Meanwhile, Chinese patent claim (02129412.7) relates to plastic/wooden boards, with the components including polyvinyl chloride (PVC), wooden flour, mineral filler, lubricant, thermal stabilizer, crosslinker, solubilizer and colorant. Its feature is that the components with the weight percentages are as follows: polyvinyl chloride PVC (45-48 wt. %), wooden flour (38-40 wt. %), mineral filler (titanium dioxide or calcium carbonate, 6-7 wt. %), N′N-Ethylene Bis Stearamide (0.8-1 wt. %) or polyethylene wax (0.3-0.5 wt. %), AC629(ethylene oxide, 0.5-0.8 wt. %) calcium stearic (0.7-0.8 wt. %), (Methyl tin mercaptide) (0.9-1 wt. %), ACR-401(3-4 wt. %) and suitable amount of colorant. While such a structure, which adopts a combination with multiple components to produce boards, resolves the problem of uneven blending between wooden flour and polyvinyl chloride, the aim of environmental protection is compromised because a large amount of wood is still being used (38-40 wt. %), and the resulting boards still have trouble maintaining the appearance and smell of wood.